A primary means of connecting two components together in a secure relationship is through the use of a threaded bolt. With threads provided in a bore of a first component, and an axially aligned bore through a second component, a threaded bolt is inserted through the bore of the second component and threadedly engaged with the threads of the bore in the first component, and by rotation of the bolt, the two components are pulled together and secured together.
Although such threaded bolt connections are extensively used, the initial securement of the two components together can be weakened in the case of vibratory or other stresses being applied to the threaded bolt connection which tend to cause the bolt to back out, even if ever so slightly, from its threaded securement. Also, under extreme stresses, a bolted connection may be severed by breakage of the bolt itself. While under normal conditions a plurality of such threaded bolt connections are used to secure two components together, such that breakage or fracturing of a single bolt will not cause separation of the components, in some instances, a bolt fragment may be separated from the remainder of the initial connection, which fragment may cause serious problems in the environment in which the two connected components are located.
In a nuclear reactor vessel environment, for example, where various components of a nuclear reactor, such as baffles, supports, or the like are secured together by threaded bolt connections, loosening or fragment dislocation can cause problems where a flow of coolant is continuously passed through the reactor. Such coolant passage could carry a bolt fragment to areas of possible damage to other reactor components. Numerous bolted connections are used in securing baffle plates to a baffle former and a baffle former to a core barrel of a nuclear reactor. Vibrations and coolant flow past the bolts can cause loosening of the bolted connections and possible fragmenting of the baffle bolts with the above-mentioned serious consequences. Such connections are, for example, described in detail in U.S. Pat. No. 4,609,102, assigned to the assignee of the present invention, and incorporated by reference herein.
As described in U.S. Pat. No. 4,069,102, the reactor internal structure for a nuclear reactor having a reactor vessel and means for circulating a liquid coolant through the vessel has a generally cylindrical core barrel supported in, and vertically oriented in, the reactor vessel, and a verticle core baffle disposed within the core barrel. The core barrel and core baffle are spaced to form an annulus between the barrel and baffle and a baffle former is disposed within the annulus. Bolted connections are used to secure the baffle former to the core barrel, and to secure baffle plates to the baffle former. The baffle plates, which are also described in U.S. Pat. No. 4,080,257, assigned to the assignee of the present invention, and incorporated by reference herein, are generally of stainless steel.
The present locking device provides a means for preventing loosening of a threaded bolt connection, and containment of fractured bolt sections within the initial location, without the need for welding. The device, due to its simplicity, is usable in applications where the connection is to be locked under submerged conditions, such as a liquid coolant, by remote controlled operation. The present device requires no special treatment, shaping or deformation of the base material and uses no springs which could wear or weaken over a period of time. The device also does not require any weakening of a bolt head such as by forming vertical or horizontal channels in the bolt head or other deformation thereof.
An improved nuclear reactor is provided through the use of the present threaded bolt connections, especially in baffle bolt connections, that provides for more secure and reliable connections of baffle plates to a baffle former, and the baffle former to the core barrel of a reactor vessel.